Podcasts about Neurospora

Play Episode Listen Later Sep 1, 1990

Two distinct pathways of sorting and assembly of nuclear-encoded mitochondrial inner membrane proteins are described. In the first pathway, precursor proteins that carry amino-terminal targeting signals are initially translocated via contact sites between both mitochondrial membranes into the mitochondrial matrix. They become proteolytically processed, interact with the 60-kDa heat-shock protein hsp60 in the matrix and are retranslocated to the inner membrane. The sorting of subunit 9 of Neurospora crassa Fo-ATPase has been studied as an example. Fo subunit 9 belongs to that class of nuclear-encoded mitochondrial proteins which are evolutionarily derived from a prokaryotic ancestor according to the endosymbiont hypothesis. We suggest that after import into mitochondria, these proteins follow the ancestral sorting and assembly pathways established in prokäryotes (conservative sorting). On the other hand, ADP/ATP carrier was found not to require interaction with hsp60 for import and assembly. This agrees with previous findings that the ADP/ATP carrier possesses non-amino-terminal targeting signals and uses a different import receptor to other mitochondrial precursor proteins. It is proposed that the ADP/ATP carrier represents a class of mitochondrial inner membrane proteins which do not have a prokaryotic equivalent and thus appear to follow a non-conservative sorting pathway.

pathways medizin sorting fo mitochondrial kda membrane proteins neurospora adp atp

Nucleotide sequence of a full-length cDNA coding for the mitochondrial precursor protein of the ß-subunit of F1-ATPase from Neurospora crassa

Play Episode Listen Later Aug 25, 1990

Sat, 25 Aug 1990 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7603/1/Neupert_Walter_7603.pdf Tropschug, Maximilian; Neupert, Walter; Müller, Harald A.; Harmey, Matthew A.; Rassow, Joachim

protein coding medizin sequence joachim precursor full length mitochondrial cdna nucleotide subunit neurospora f1 atpase neupert walter

Matrix processing peptidase of mitochondria

Play Episode Listen Later Jan 1, 1990

The mitochondrial processing peptidase (MPP) and the processing enhancing protein (PEP) cooperate in the proteolytic cleavage of matrix targeting sequences from nuclear-encoded mitochondrial precursor proteins. We have determined the cDNA sequence of Neurospora MPP after expression cloning. MPP appears to contain two domains of approximately equal size which are separated by a loop-like sequence. Considerable structural similarity exists to the recently sequenced yeast MPP as well as to Neurospora and yeast PEP. Four cysteine residues are conserved in Neurospora and yeast MPP. Inactivation of MPP can be achieved by using sulfhydryl reagents. MPP (but not PEP) depends on the presence of divalent metal ions for activity. Both MPP and PEP are synthesized as precursors containing matrix targeting signals which are processed during import into mitochondria by the mature forms of MPP and PEP.

matrix processing medizin pep mitochondria mpp cdna inactivation neurospora peptidase

Import of ADP/ATP carrier into mitochondria

Play Episode Listen Later Jan 1, 1990

We have identified the yeast homologue of Neurospora crassa MOM72, the mitochondrial import receptor for the ADP/ATP carrier (AAC), by functional studies and by cDNA sequencing. Mitochondria of a yeast mutant in which the gene for MOM72 was disrupted were impaired in specific binding and import of AAC. Unexpectedly, we found a residual, yet significant import of AAC into mitochondria lacking MOM72 that occurred via the receptor MOM19. We conclude that both MOM72 and MOM19 can direct AAC into mitochondria, albeit with different efficiency. Moreover, the precursor of MOM72 apparently does not require a positively charged sequence at the extreme amino terminus for targeting to mitochondria.

import medizin carrier aac unexpectedly mitochondria cdna neurospora adp atp mom19 mom72

Sensitivity to cyclosporin A is mediated by cyclophilin in Neurospora crassa and Saccharomyces cerevisiae

Play Episode Listen Later Dec 28, 1989

Thu, 28 Dec 1989 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7541/1/Neupert_Walter_7541.pdf Neupert, Walter; Barthelmess, Ilse B.; Tropschug, Maximilian

sensitivity medizin mediated saccharomyces cerevisiae neurospora cyclosporin neupert walter

Translocation arrest by reversible folding of a precursor protein imported into mitochondria

Play Episode Listen Later Jan 1, 1989

Passage of precursor proteins through translocation contact sites of mitochondria was investigated by studying the import of a fusion protein consisting of the NH2-terminal 167 amino acids of yeast cytochrome b2 precursor and the complete mouse dihydrofolate reductase. Isolated mitochondria of Neurospora crassa readily imported the fusion protein. In the presence of methotrexate import was halted and a stable intermediate spanning both mitochondrial membranes at translocation contact sites accumulated. The complete dihydrofolate reductase moiety in this intermediate was external to the outer membrane, and the 136 amino acid residues of the cytochrome b2 moiety remaining after cleavage by the matrix processing peptidase spanned both outer and inner membranes. Removal of methotrexate led to import of the intermediate retained at the contact site into the matrix. Thus unfolding at the surface of the outer mitochondrial membrane is a prerequisite for passage through translocation contact sites. The membrane-spanning intermediate was used to estimate the number of translocation sites. Saturation was reached at 70 pmol intermediate per milligram of mitochondrial protein. This amount of translocation intermediates was calculated to occupy approximately 1% of the total surface of the outer membrane. The morphometrically determined area of close contact between outer and inner membranes corresponded to approximately 7% of the total outer membrane surface. Accumulation of the intermediate inhibited the import of other precursor proteins suggesting that different precursor proteins are using common translocation contact sites. We conclude that the machinery for protein translocation into mitochondria is present at contact sites in limited number.

arrest protein passage removal medizin isolated folding mitochondria saturation accumulation precursor imported reversible translocation neurospora nh2

Role of cytochrome c heme lyase in the import of cytochrome c into mitochondria

conversion formation import medizin mitochondria heme cytochrome neurospora

Play Episode Listen Later Dec 15, 1988

The import of cytochrome c into Neurospora crassa mitochondria was examined at distinct stages in vitro. The precursor protein, apocytochrome c, binds to mitochondria with high affinity and specificity but is not transported completely across the outer membrane in the absence of conversion to holocytochrome c. The bound apocytochrome c is accessible to externally added proteases but at the same time penetrates far enough through the outer membrane to interact with cytochrome c heme lyase. Formation of a complex in which apocytochrome c and cytochrome c heme lyase participate represents the rate-limiting step of cytochrome c import. Conversion from the bound state to holocytochrome c, on the other hand, occurs 10-30-fold faster. Association of apocytochrome c with cytochrome c heme lyase also takes place after solubilizing mitochondria with detergent. We conclude that the bound apocytochrome c, spanning the outer membrane, forms a complex with cytochrome c heme lyase from which it can react further to be converted to holocytochrome c and be translocated completely into the intermembrane space.

Cyclosporin A-binding protein (cyclophilin) of Neurospora crassa

Play Episode Listen Later Oct 5, 1988

Cyclophilin (cyclosporin A-binding protein) has a dual localization in the mitochondria and in the cytosol of Neurospora crassa. The two forms are encoded by a single gene which is transcribed into mRNAs having different lengths and 5' termini (approximately 1 and 0.8 kilobases). The shorter mRNA specifies the cytosolic protein consisting of 179 amino acids. The longer mRNA is translated into a precursor polypeptide with an amino-terminal extension of 44 amino acids which is cleaved in two steps upon entry into the mitochondrial matrix. Neurospora cyclophilin shows about 60% sequence homology to human and bovine cyclophilins.

protein medizin mrna binding mrnas neurospora cyclosporin

A mutant of Neurospora crassa deficient in cytochrome c heme lyase activity cannot import cytochrome c into mitochondria

Play Episode Listen Later Jul 5, 1988

The nuclear cyt-2-1 mutant of Neurospora crassa is characterized by a gross deficiency of cytochrome c (Bertrand, H., and Collins, R. A. (1978) Mol. Gen. Genet. 166, 1-13). The mutant produces mRNA that can be translated into apocytochrome c in vitro. Apocytochrome c is also synthesized in vivo in cyt-2-1, but it is rapidly degraded and thus does not accumulate in the cytosol. Mitochondria from wild-type cells bind apocytochrome c made in vitro from either wild-type or cyt-2-1 mRNA and convert it to holocytochrome c. This conversion depends on the addition of heme by cytochrome c heme lyase and is coupled to translocation of cytochrome c into the intermembrane space. Mitochondria from the cyt-2-1 strain are deficient in the ability to bind apocytochrome c. They are also completely devoid of cytochrome c heme lyase activity. These defects explain the inability of the cyt-2-1 mutant to convert apocytochrome c to the holo form and to import it into mitochondria.

activity import medizin mrna mutant bertrand mitochondria mol deficient heme genet cytochrome neurospora apocytochrome

Mitochondrial protein import

protein transport import medizin pep mpp mitochondrial neurospora

Play Episode Listen Later Jun 3, 1988

Transport of nuclear-encoded precursor proteins into mitochondria includes proteolytic cleavage of aminoterminal targeting sequences in the mitochondrial matrix. We have isolated the processing activity from Neurospora crassa. The final preparation (enriched ca. 10,000-fold over cell extracts) consists of two proteins, the matrix processing peptidase (MPP, 57 kd) and a processing enhancing protein (PEP, 52 kd). The two components were isolated as monomers. PEP is about 15-fold more abundant in mitochondria than MPP. It is partly associated with the inner membrane, while MPP is soluble in the matrix. MPP alone has a low processing activity whereas PEP alone has no apparent activity. Upon recombining both, full processing activity is restored. Our data indicate that MPP contains the catalytic site and that PEP has an enhancing function. The mitochondrial processing enzyme appears to represent a new type of “signal peptidase,” different from the bacterial leader peptidase and the signal peptidase of the endoplasmic reticulum.

Mitochondrial precursor proteins are imported through a hydrophilic membrane environment

Play Episode Listen Later Dec 1, 1987

We have analyzed how translocation intermediates of imported mitochondrial precursor proteins, which span contact sites, interact with the mitochondrial membranes. F1-ATPase subunit β(F1β) was trapped at contact sites by importing it into Neurospora mitochondria in the presence of low levels of nucleoside triphosphates. This F1β translocation intermediate could be extracted from the membranes by treatment with protein denaturants such as alkaline pH or urea. By performing import at low temperatures, the ADP/ATP carrier was accumulated in contact sites of Neurospora mitochondria and cytochrome b2 in contact sites of yeast mitochondria. These translocation intermediates were also extractable from the membranes at alkaline pH. Thus, translocation of precursor proteins across mitochondrial membranes seems to occur through an environment which is accessible to aqueous perturbants. We propose that proteinaceous structures are essential components of a translocation apparatus present in contact sites.

environment f1 medizin proteins precursor membrane imported mitochondrial neurospora hydrophilic adp atp f1 atpase

Mitochondrial porin of Neurospora crassa

medizin mitochondrial cdna porin neurospora

Play Episode Listen Later Sep 1, 1987

cDNA encoding porin of Neurospora crassa, the major protein component of the outer mitochondrial membrane, was isolated and the nucleotide sequence was determined. The deduced protein sequence consists of 283 amino acids (29,979 daltons) and shows sequence homology of around 43% to yeast porin; however, no significant homology to bacterial porins was apparent. According to secondary structure predictions, mitochondrial porin consists mainly of membrane-spanning sided beta-sheets. Porin was efficiently synthesized in vitro from the cDNA; this allowed us to study in detail its import into mitochondria. Thereby, three characteristics of import were defined: (i) import depended on the presence of nucleoside triphosphates; (ii) involvement of a proteinaceous receptor-like component on the surface of the mitochondria was demonstrated; (iii) insertion into the outer membrane was resolved into at least two distinct steps: specific binding to high-affinity sites and subsequent assembly to the mature form.

Deficiency in mRNA splicing in a cytochrome c mutant of neurospora crassa

dna southern medizin mrna mutant sequence molecular deficiency splicing cdna cytochrome neurospora

Play Episode Listen Later Jul 1, 1987

Molecular cloning and characterization of cytochrome c cDNA clones of Neurospora crassa wild-type (74A) and a cytochrome c-deficient mutant (cyc1-1) are described. Southern blot analysis of genomic DNA indicates that only one cytochrome c gene exists in the N. crassa genome. The cDNA sequence of the wild-type cytochrome c confirmed the previously determined protein sequence. Sequence analysis of the cyc1-1 cDNA for cytochrome c revealed the presence of a larger open reading frame, owing to the presence of an unspliced intron in the 3' end of the coding region. Splicing of this intron is obviously prevented due to the presence of two base exchanges in the highly conserved intron consensus sequences. Consequently, cyc1-1 synthesizes apocytochrome c with an altered carboxy terminus, 19 amino acids longer than the wild-type cytochrome c, with the final 27 amino acids being of an unrelated sequence. This alteration in the carboxy terminus renders the apocytochrome c incompetent for binding to mitochondria and, consequently, import into mitochondria. Thus, unlike other mitochondrial precursor proteins, where it has been demonstrated that the amino terminus alone is sufficient to target the protein to the mitochondria, an intact carboxy terminus is required for efficient import of apocytochrome c into mitochondria. This is independent confirmation for the view that the import pathway of cytochrome c is unique with respect to all other mitochondrial proteins studied to date.

Import of cytochrome c into mitochondria

Medizin - Open Access LMU - Teil 05/22

Play Episode Listen Later Apr 1, 1987

The import of cytochrome c into mitochondria can be resolved into a number of discrete steps. Here we report on the covalent attachment of heme to apocytochrome c by the enzyme cytochrome c heme lyase in mitochondria from Neurospora crassa. A new method was developed to measure directly the linkage of heme to apocytochrome c. This method is independent of conformational changes in the protein accompanying heme attachment. Tryptic peptides of [35S]cysteine-labelled apocytochrome c, and of enzymatically formed holocytochrome c, were resolved by reverse-phase HPLC. The cysteine-containing peptide to which heme was attached eluted later than the corresponding peptide from apocytochrome c and could be quantified by counting 35S radioactivity as a measure of holocytochrome c formation. Using this procedure, the covalent attachment of heme to apocytochrome c, which is dependent on the enzyme cytochrome c heme lyase, could be measured. Activity required heme (as hemin) and could be reversibly inhibited by the analogue deuterohemin. Holocytochrome c formation was stimulated 5–10-fold by NADH > NADPH > glutathione and was independent of a potential across the inner mitochondrial membrane. NADH was not required for the binding of apocytochrome c to mitochondria and was not involved in the reduction of the cysteine thiols prior to heme attachment. Holocytochrome c formation was also dependent on a cytosolic factor that was necessary for the heme attaching step of cytochrome c import. The factor was a heat-stable, protease-insensitive, low-molecular-mass component of unknown function. Cytochrome c heme lyase appeared to be a soluble protein located in the mitochondrial intermembrane space and was distinct from the previously identified apocytochrome c binding protein having a similar location. A model is presented in which the covalent attachment of heme by cytochrome c heme lyase also plays an essential role in the import pathway of cytochrome c.

activity import medizin mitochondria nadh hplc nadph cytochrome neurospora 35s

A water-soluble form of porin from the mitochondrial outer membrane of Neurospora crassa

Play Episode Listen Later Jul 5, 1985

Mitochondrial porin, the outer membrane pore-forming protein, was isolated in the presence of detergents and converted into a water- soluble form. This water-soluble porin existed under nondenaturing conditions as a mixture of dimers and oligomers. The proportion of dimers increased with decreasing porin concentration during conversion. Water-soluble porin inserted spontaneously into artificial bilayers as did detergent-solubilized porin. Whereas the latter form had no specific requirements for the lipid composition of the bilayer, water- soluble porin inserted only into membranes containing a sterol, and only in the presence of very low concentrations of Triton X-100 (0.001% w/v) in the solution bathing the bilayer. The channels formed by water- soluble porin were indistinguishable from those formed by detergent- purified porin with respect to specific conductance and voltage dependence of conductance. Water-soluble porin bound tightly in a saturable fashion to isolated mitochondria. The bound form was readily accessible to added protease, indicating its presence on the mitochondrial surface. The number of binding sites was in the range of 5-10 pmol/mg of mitochondrial protein. Water-soluble porin apparently binds to a site on the assembly pathway of the porin precursor, since mitochondria whose binding sites were saturated with the water-soluble form did not import porin precursor synthesized in a cell-free system.

water medizin outer membrane mitochondrial soluble porin neurospora triton x

Processing peptidase of Neurospora mitochondria

Play Episode Listen Later Nov 1, 1984

Subunit 9 (dicyclohexylcarbodiimide binding protein, 'proteolipid') of the mitochondrial F1F0-ATPase is a nuclearly coded protein in Neurospora crassa. It is synthesized on free cytoplasmic ribosomes as a larger precursor with an NH2-terminal peptide extension. The peptide extension is cleaved off after transport of the protein into the mitochondria. A processing activity referred to as processing peptidase that cleaves the precursor to subunit 9 and other mitochondrial proteins is described and characterized using a cell-free system. Precursor synthesized in vitro was incubated with extracts of mitochondria. Processing peptidase required Mn2+ for its activity. Localization studies suggested that it is a soluble component of the mitochondrial matrix. The precursor was cleaved in two sequential steps via an intermediate-sized polypeptide. The intermediate form in the processing of subunit 9 was also seen in vivo and upon import of the precursor into isolated mitochondria in vitro. The two cleavage sites in the precursor molecule were determined. The data indicate that: (a) the correct NH2-terminus of the mature protein was generated, (b) the NH2-terminal amino acid of the intermediate-sized polypeptide is isoleucine in position-31. The cleavage sites show similarity of primary structure. It is concluded that processing peptidase removes the peptide extension from the precursor to subunit 9 (and probably other precursors) after translocation of these polypeptides (or the NH2-terminal part of these polypeptides) into the matrix space of mitochondria.

processing medizin mitochondria precursor localization subunit neurospora peptidase nh2 mn2

Proteinaceous receptors for the import of mitochondrial precursor proteins

Play Episode Listen Later Jun 25, 1984

Mild trypsin treatment of isolated Neurospora mitochondria strongly inhibits their ability to bind and import the precursors of several mitochondrial proteins. Evidence is presented for two proteins, the ADP/ATP carrier and the mitochondrial porin, that specific binding of the precursors to the outer surface of the mitochondria is affected by the protease treatment. We suggest that the receptors that mediate the import of these two precursors are proteinaceous. Treatment of mitochondria with elastase also inhibits the binding and import of the ADP/ATP carrier and the porin. In contrast the import of the precursors of subunits 2 and 9 of the mitochondrial proton-translocating ATPase was unaffected by elastase treatment at the concentrations used. We suggest that the import pathways of the latter two proteins are distinct from those of the ADP/ATP carrier and the porin.

treatments import medizin mild proteins precursor mitochondrial receptors atpase neurospora adp atp

Receptor sites involved in posttranslational transport of apocytochrome c into mitochondria

Play Episode Listen Later Aug 1, 1983

Assembly of cytochrome c involves a series of steps: synthesis of apocytochrome c on free ribosomes, specific binding of apocytochrome c to the mitochondrial surface, transfer across the outer membrane, covalent addition of protoheme, refolding of the polypeptide chain, and association of holocytochrome c with its functional sites at the inner membrane. The binding step of apocytochrome c to Neurospora crassa mitochondria was studied by inhibiting the subsequent transfer steps with the heme analogue deuterohemin. The binding sites are highly specific for mitochondrial apocytochromes c. Bound labeled Neurospora apocytochrome c was competitively displaced by unlabeled apocytochrome c from various species. These exhibited different abilities for displacement. Apocytochrome c from Paracoccus denitrificans, the amino-terminal (heme-binding) fragment of Neurospora apocytochrome c, and Neurospora holocytochrome c did not recognize the binding sites. Polylysine did not interfere with apocytochrome c binding. Apocytochrome c is reversibly bound. The binding sites are present in limited number. High-affinity binding sites were present at about 90 pmol/mg of mitochondrial protein. They displayed an association constant of 2.2 X 10(7) M-1. Apocytochrome c was imported into mitochondria and converted to holocytochrome c directly from the binding sites when inhibition by deuterohemin was relieved. We conclude that the apocytochrome c binding sites on mitochondria represent receptors that function in the recognition and import of this precursor by mitochondria.

bound transport involved sites assembly medizin mitochondria receptor neurospora apocytochrome

Transport of the precursor to neurospora ATPase subunit 9 into yeast mitochondria

Play Episode Listen Later Apr 25, 1983

Isolated yeast mitochondria were able to take up Neurospora ATPase subunit 9 in vitro although the homologous yeast protein is synthesized within the mitochondria and inserted into the membrane from the matrix side (Tzagoloff, A., and Meagher, P. (1972) J. Biol. Chem. 247, 594- 603). The transfer of the protein was dependent on an energized mitochondrial inner membrane. It was accompanied by proteolytic processing of the precursor to the mature protein with the correct NH2 terminus as determined by Edman degradation of the transferred protein. The possibility is discussed that there are common features in the uptake machinery neither specific for one species nor specific for individual precursor proteins in the same species.

transport medizin isolated yeast biol mitochondria precursor chem meagher edman atpase subunit neurospora nh2

Transfer of proteins into mitochondria

Play Episode Listen Later Apr 10, 1983

The precursor form of Neurospora crassa mitochondrial ADP/ATP carrier synthesized in a cell-free protein-synthesizing system can be imported into isolated mitochondria. If the mitochondrial transmembrane potential is abolished, import does not occur but the precursor binds to the mitochondrial surface. Upon reestablishment of the membrane potential, the bound precursor is imported. This occurs without dissociation of the bound precursor from the mitochondrial surface. We conclude that the binding observed represents an interaction with receptor sites and thus is an early step in the import pathway.

medizin proteins mitochondria neurospora adp atp

Isolation and properties of the porin of the outer mitochondrial membrane from Neurospora crassa

isolation properties medizin outer benz helmut membrane mitochondrial porin neurospora

Play Episode Listen Later Jan 1, 1983

Sat, 1 Jan 1983 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7400/1/7400.pdf Neupert, Walter; Benz, Roland; Freitag, Helmut

Biosynthetic pathway of mitochondrial ATPase subunit 9 in Neurospora crassa

Play Episode Listen Later Jan 1, 1983

Subunit 9 of mitochondrial ATPase (Su9) is synthesized in reticulocyte lysates programmed with Neurospora poly A-RNA, and in a Neurospora cell free system as a precursor with a higher apparent molecular weight than the mature protein (Mr 16,400 vs. 10,500). The RNA which directs the synthesis of Su9 precursor is associated with free polysomes. The precursor occurs as a high molecular weight aggregate in the postribosomal supernatant of reticulocyte lysates. Transfer in vitro of the precursor into isolated mitochondria is demonstrated. This process includes the correct proteolytic cleavage of the precursor to the mature form. After transfer, the protein acquires the following properties of the assembled subunit: it is resistant to added protease, it is soluble in chloroform/methanol, and it can be immunoprecipitated with antibodies to F1-ATPase. The precursor to Su9 is also detected in intact cells after pulse labeling. Processing in vivo takes place posttranslationally. It is inhibited by the uncoupler carbonylcyanide m- chlorophenylhydrazone (CCCP). A hypothetical mechanism is discussed for the intracellular transfer of Su9. It entails synthesis on free polysomes, release of the precursor into the cytosol, recognition by a receptor on the mitochondrial surface, and transfer into the inner mitochondrial membrane, which is accompanied by proteolytic cleavage and which depends on an electrical potential across the inner mitochondrial membrane.

processing pathway medizin rna mitochondrial cccp atpase subunit biosynthetic neurospora f1 atpase

Biogenesis of cytochrome c in Neurospora crassa

medizin bernd hennig biogenesis cytochrome neurospora

Play Episode Listen Later Jan 1, 1983

Sat, 1 Jan 1983 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7398/1/7398.pdf Neupert, Walter; Hennig, Bernd ddc:610, Medizin

Biosynthesis and assembly of nuclear-coded mitochondrial membrane proteins in Neurospora crassa

Play Episode Listen Later Jan 1, 1983

Sat, 1 Jan 1983 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7399/1/7399.pdf Neupert, Walter; Zimmermann, Richard

nuclear assembly medizin zimmermann coded mitochondrial biosynthesis membrane proteins neurospora

Biogenesis of mitochondrial ubiquinol

iv viii medizin vii mitochondrial biogenesis ubiquinol neurospora

Play Episode Listen Later Sep 10, 1982

The precursor proteins to the subunits of ubiquinol:cytochrome c reductase (cytochrome bc1 complex) of Neurospora crassa were synthesized in a reticulocyte lysate. These precursors were immunoprecipitated with antibodies prepared against the individual subunits and compared to the mature subunits immunoprecipitated or isolated from mitochondria. Most subunits were synthesized as precursors with larger apparent molecular weights (subunits I, 51,500 versus 50,000; subunit II, 47,500 versus 45,000; subunit IV (cytochrome c1), 38,000 versus 31,000; subunit V (Fe-S protein), 28,000 versus 25,000; subunit VII, 12,000 versus 11,500; subunit VIII, 11,600 versus 11,200). Subunit VI (14,000) was synthesized with the same apparent molecular weight. The post-translational transfer of subunits I, IV, V, and VII was studied in an in vitro system employing reticulocyte lysate and isolated mitochondria. The transfer and proteolytic processing of these precursors was found to be dependent on the mitochondrial membrane potential. In the transfer of cytochrome c1, the proteolytic processing appears to take place in two separate steps via an intermediate both in vivo and in vitro. In vivo, the intermediate form accumulated when cells were kept at 8 degrees C and was chased into mature cytochrome c1 at 25 degrees C. Both processing steps were energy- dependent.

Isolation of mitochondrial porin from Neurospora crassa

Play Episode Listen Later Aug 16, 1982

Mon, 16 Aug 1982 12:00:00 +0100 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T36-448HVHC-10J&_user=616146&_coverDate=08%2F16%2F1982&_rdoc=16&_fmt=high&_orig=browse&_srch=doc-info(%23toc%234938%231982%23998549998%23268913%23FLP%23display%23Volume)&_cdi=4938&_sort=d&_docanch https://epub.ub.uni-muenchen.de/7397/1/Neupert_Walter_7397.pdf Neupert, Walter; Palmieri, Ferdinando; Benz, Roland; Genchi, Giuseppe; Freitag, Helmut ddc:610, Medizin

isolation medizin giuseppe benz helmut palmieri mitochondrial ferdinando porin neurospora articleurl genchi neupert walter coverdate 23volume 23flp

Structural role of the tyrosine residues of cytochrome c

medizin structural tyrosine residues cytochrome neurospora

Play Episode Listen Later Jul 1, 1982

The tertiary structures of horse, tuna, Neurospora crassa, horse [Hse65,Leu67]- and horse [Hse65,Leu74]-cytochromes c were studied with high-resolution 1H n.m.r. spectroscopy. The amino acid sequences of these proteins differ at position 46, which is occupied by phenylalanine in the horse proteins but by tyrosine in the remaining two, and at positions 67, 74 and 97, which are all occupied by tyrosine residues in horse and tuna cytochrome c but in the other proteins are substituted by phenylalanine or leucine, though there is only one such substitution per protein. The various aromatic-amino-acid substitutions do not seriously affect the protein structure.

Requirement of a Membrane Potential for the Posttranslational Transfer of Proteins into Mitochondsria

Play Episode Listen Later Jun 1, 1982

Posttranslational transfer of most precursor proteins into mitochondria is dependent on energization of the mitochondria. Experiments were carried out to determine whether the membrane potential or the intramitochondrial ATP is the immediate energy source. Transfer in vitro of precursors to the ADP/ATP carrier and to ATPase subunit 9 into isolated Neurospora mitochondria was investigated. Under conditions where the level of intramitochondrial ATP was high and the membrane potential was dissipated, import and processing of these precursor proteins did not take place. On the other hand, precursors were taken up and processed when the intramitochondrial ATP level was low, but the membrane potential was not dissipated. We conclude that a membrane potential is involved in the import of those mitochondrial precursor proteins which require energy for intracellular translocation

experiments requirements medizin atp proteins membrane atpase neurospora adp atp

Biosynthesis Of Glyoxysomal Enzymes In Neurospora Crassa

Play Episode Listen Later May 1, 1982

Sat, 1 May 1982 12:00:00 +0100 http://www3.interscience.wiley.com/journal/119560512/abstract https://epub.ub.uni-muenchen.de/7396/1/Neupert_Walter_7396.pdf Neupert, Walter; Miller, Fritz; Janes, Michael; Zimmermann, Richard; Desel, Herbert ddc:610, Medizin

herbert fritz medizin zimmermann janes enzymes biosynthesis neurospora neupert walter

Purification and Characterisation of a Pore Protein of the Outer Mitochondrial Membrane from Neurospora crassa

single protein medizin outer purification membrane mitochondrial pore characterisation neurospora

Play Episode Listen Later Jan 1, 1982

The major protein of the outer mitochondrial membrane of Neurospora was purified. On dodecylsulfate-containing gels it displayed a single bend with an apparent molecular weight of 31000. reconstitution experiments with artifical lipid bilayers showed that this protein forms pores. Pore conductance was dependent on the voltage across the membrane. The protein inserted into the membrane in an oriented fashion, the membrane current being dependent on the sign of the voltage. Single pore conductance was 5nS, suggesting a diameter of 2nm of the open pore. This mitochondrial protein shows a number of similarities to the outer membrane porins of gram-negative bacteria.

Assembly of Cytochrome c

Play Episode Listen Later Dec 1, 1981

Transport of apocytochrome c across the outer mitochondrial membrane and conversion to holocytochrome c were studied in vitro. Apocytochrome c was synthesized in a cell-free homogenate from Neurospora crassa. Transfer in vitro was accomplished in a reconstituted system consisting of the postribosomal supernatant of the cell-free homogenate and of isolated and purified mitochondria from Neurospora. The reconstituted system has the following characteristics: * 1. Apocytochrome c is rapidly cleared from the supernatant and holocytochrome c appears in the mitochondria with the same kinetics. More than 80% of the apocytochrome c employed is converted to holocytochrome c. No transient accumulation of apocytochrome c is found in mitochondria. * 2. The heme group becomes covalently linked to apocytochrome c in the reconstituted system as demonstrated by analysis of tryptic peptide maps of the apoprotein and holoprotein. * 3. Deuterohemin added to the reconstituted system but not deuteroporphyrin inhibits the formation of holocytochrome c. This inhibition is reversed by protohemin. * 4. In the presence of deuterohemin about half of the apocytochrome c remains in the supernatant; the other half becomes associated with the mitochondria. The latter portion is tightly bound and is specifically released upon incubation of the mitochondria with excess apocytochrome c. It is converted to holocytochrome c after addition of protohemin. We conclude from these observations that apocytochrome c is transported across the outer mitochondrial membrane via receptor sites. In the presence of the heme analogue deuterohemin, binding to the receptor sites on the cytoplasmic surface of the outer mitochondrial membrane still takes place but translocation does not. The latter step is apparently coupled to the covalent linkage of the heme group. We suggest that the formation of the thioether bonds between apoprotein and heme is catalysed by an enzyme in the intermembrane space and that deuterohemin can compete with protohemin for binding to the enzyme. Finally, the data indicate that it is the heme group and not the porphyrin group which is coupled to the apoprotein.

transport assembly medizin cytochrome neurospora apocytochrome

Different Transport Pathways of Individual Precursor Proteins in Mitochondria

Play Episode Listen Later Jun 1, 1981

Transport of mitochondrial precursor proteins into mitochondria of Neurospora crassa was studied in a cellfree reconstituted system. Precursors were synthesized in a reticulocyte lysate programmed with Neurospora mRNA and transported into isolated mitochondria in the absence of protein synthesis. Uptake of the following precursors was investigated: apocytochrome c, ADP/ATP carrier and subunit 9 of the oligomycin-sensitive ATPase. Addition of high concentrations of unlabelled chemically prepared apocytochrome c (1–10 μM) inhibited the appearance in the mitochondrial of labelled cytochrome c synthesized in vitro because the unlabelled protein dilutes the labelled one and because the translocation system has a limited capacity [apparent V is 1–3 pmol × min−1× (mg mitochondrial protein)−1]. Concentrations of added apocytochrome c exceeding the concentrations of precursor proteins synthesized in vitro by a factor of about 104 did not inhibit the transfer of ADP/ATP carrier or ATPase subunit 9 into mitochondria. Carbonylcyanide m-chlorophenylhydrazone, an uncoupler of oxidative phosphorylation, inhibited transfer in vitro of ADP/ATP carrier and of ATPase subunit 9, but not of cytochrome c. These findings suggest that cytochrome c and the other two proteins have different import pathways into mitochondria. It can be inferred from the data presented that different 'receptors' on the mitochondrial surface mediate the specific recognition of precursor proteins by mitochondria as a first step in the transport process.

individual transport pathways addition medizin proteins mitochondria precursor uptake precursors concentrations atpase neurospora adp atp

Biogenesis of Glyoxysomes

Play Episode Listen Later Nov 1, 1980

Biosynthesis of isocitrate lyase, a tetrameric enzyme of the glyoxysomal matrix, was studied in Neurospora crassa, in which the formation of glyoxysomes was induced by a substitution of sucrose medium by acetate medium. * 1. Translation of Neurospora mRNA in reticulocyte lysates yields a product which has the same apparent molecular weight as the subunit of the functional enzyme. Using N-formyl[35S]methionyl tRNAMetf as a label, the translation product shows the same apparent size which indicates that the amino terminus has no additional 'signal'-type sequence. * 2. Read-out systems employing free and membrane-bound polysomes show that only free ribosomes are active in the synthesis of isocitrate lyase. * 3. Isocitrate lyase synthesized in reticulocyte lysate is released into the supernatant and is soluble in a monomeric form. It interacts with Triton X-100 to form mixed micells in contrast to the functional tetrameric form. * 4. Transfer of isocitrate lyase synthesized in vitro into isolated glyoxysomes is suggested by results of experiments in which supernatants from reticulocyte lysates are incubated with a particle fraction isolated from acetate-grown cells. No transfer occurs when particles from non-induced cells are employed. Resistance to added proteinase is used as a criterion for transmembrane transfer. The data support a post-translational transfer mechanism for isocitrate lyase. They suggest that isocitrate lyase passes through a cytosolic precurscr pool as a monomer and is transferred into glyoxysomes.

resistance translation medizin biogenesis biosynthesis neurospora 35s triton x

Transport of Proteins into Mitochondria

Play Episode Listen Later Jan 1, 1980

The mitochondrial ADP/ATP carrier is an integral transmembrane protein of the inner membrane. It is synthesized on cytoplasmic ribosomes. Kinetic data suggested that this protein is transferred into mitochondria in a posttranslational manner. The following results provide further evidence for such a mechanism and provide information on its details. 1. In homologous and heterologous translation systems the newly synthesized ADP/ATP carrier protein is present in the postribosomal supernatant. 2. Analysis by density gradient centrifugation and gel filtration shows, that the ADP/ATP carrier molecules in the postribosomal fraction are present as soluble complexes with apparent molecular weights of about 120000 and 500000 or larger. The carrier binds detergents such as Triton X-100 and deoxycholate forming mixed micelles with molecular weights of about 200000–400000. 3. Incubation of a postribosomal supernatant of a reticulocyte lysate containing newly synthesized ADP/ATP carrier with mitochondria isolated from Neurospora spheroplasts results in efficient transfer of the carrier into mitochondria. About 20–30% of the transferred carrier are resistant to proteinase in whole mitochondria. The authentic mature protein is also largely resistant to proteinase in whole mitochondria and sensitive after lysis of mitochondria with detergent. Integrity of mitochondria is a prerequisite for translocation into proteinase resistant position. 4. The transfer in vitro into a proteinase-resistant form is inhibited by the uncoupler carbonyl-cyanide m-chlorophenylhydrazone but not the proteinase-sensitive binding. These observations suggest that the posttranslational transfer of ADP/ATP carrier occurs via the cytosolic space through a soluble oligomeric precursor form. This precursor is taken up by intact mitochondria into an integral position in the membrane. These findings are considered to be of general importance for the intracellular transfer of insoluble membrane proteins. They support the view that such proteins can exist in a water-soluble form its precursors and upon integration into the membrane undergo a conformational change. Uptake into the membrane may involve the cleavage of an additional sequence in some proteins, but this appears not to be a prerequisite as demonstrated by the ADP/ATP carrier protein.

integrity analysis transport medizin proteins mitochondria kinetic incubation uptake neurospora adp atp triton x

Biosynthesis of mitochondrial citrate synthase in neurospora crassa

Play Episode Listen Later Dec 1, 1979

Sat, 1 Dec 1979 12:00:00 +0100 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T36-44DSR1F-B5&_user=616146&_coverDate=12%2F15%2F1979&_rdoc=18&_fmt=high&_orig=browse&_srch=doc-info(%23toc%234938%231979%23998919997%23272157%23FLP%23display%23Volume)&_cdi=4938&_sort=d&_docancho https://epub.ub.uni-muenchen.de/7342/1/Neupert_Walter_7342.pdf Neupert, Walter; Harmey, Matthew A. ddc:610, Medizin

medizin mitochondrial citrate biosynthesis synthase neurospora articleurl neupert walter 23volume coverdate 23flp

Cell-Free Synthesis of the Mitochondrial ADP/ATP Carrier Protein of Neurospora crassa

Play Episode Listen Later Sep 1, 1979

ADP/ATP carrier protein was synthesized in heterologous cell-free systems programmed with Neurospora poly(A)-containing RNA and homologous cell-free systems from Neurospora. The apparent molecular weight of the product obtained in vitro was the same as that of the authentic mitochondrial protein. The primary translation product obtained in reticulocyte lysates starts with formylmethionine when formylated initiator methionyl-tRNA (fMet-tRNAfMet) was present. The product synthesized in vitro was released from the ribosomes into the postribosomal supernatant. The evidence presented indicates that the ADP/ATP carrier is synthesized as a polypeptide with the same molecular weight as the mature monomeric protein and does not carry an additional sequence.

protein medizin carrier rna synthesis mitochondrial cell free neurospora adp atp

Mitochondrial ribosomes of neurospora crassa

Play Episode Listen Later Jan 1, 1979

Mon, 1 Jan 1979 12:00:00 +0100 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7CV2-4B3VKS2-98&_user=616146&_coverDate=12%2F31%2F1979&_rdoc=12&_fmt=high&_orig=browse&_srch=doc-info(%23toc%2318066%231979%23999439999%23472572%23FLA%23display%23Volume)&_cdi=18066&_sort=d&_docanc https://epub.ub.uni-muenchen.de/7321/1/7321.pdf Hallermayer, Gerhard; Michel, Rainer; Miller, Fritz; Neupert, Walter ddc:610, Medizin

fritz medizin rainer gerhard mitochondrial neurospora articleurl coverdate 23volume

Biogenesis of Cytochrome c in Neurospora crassa

Play Episode Listen Later Nov 1, 1978

# 1. Precipitating antibodies specific for apocytochrome c and holocytochrome c, respectively, were employed to study synthesis and intracellular transport of cytochrome c in Neurospora in vitro. # 2. Apocytochrome c as well as holocytochrome c were found to be synthesized in a cell-free homogenate. A precursor product relationship between the two components is suggested by kinetic experiments. # 3. Apocytochrome c synthesized in vitro was found in the post-ribosomal fraction and not in the mitochondrial fraction, whereas holocytochrome c synthesized in vitro was mainly detected in the mitochondrial fraction. A precursor product relationship between postribosomal apocytochrome c and mitochondrial holocytochrome c is indicated by the labelling data. In the microsomal fraction both apocytochrome c and holocytochrome c were found in low amounts. Their labelling kinetics do not suggest a precursor role of microsomal apocytochrome c or holocytochrome c. # 4. Formation of holocytochrome c from apocytochrome c was observed when postribosomal supernatant containing apocytochrome c synthesized in vitro was incubated with isolated mitochondria, but not when incubated in the absence of mitochondria. The cytochrome c formed under these conditions was detected in the mitochondria. # 5. Conversion of labelled apocytochrome c synthesized in vitro to holocytochrome c during incubation of a postribosomal supernatant with isolated mitochondria was inhibited when excess isolated apocytochrome c, but not when holocytochrome c was added. # 6. The data presented are interpreted to show that apocytochrome c is synthesized on cytoplasmic ribosomes and released into the supernatant. It is suggested that apocytochrome c migrates to the inner mitochondrial membrane, where the heme group is covalently linked to the apoprotein. The hypothesis is put forward that the concomitant change in conformation leads to trapping of holocytochrome c in the membrane. The probles of permeability of the outer mitochondrial membrane to apocytochrome c and the site and nature of the reaction by which the heme group is linked to the apoprotein are discussed.

conversion formation medizin biogenesis cytochrome neurospora precipitating apocytochrome

Preparation of Neurospora crassa mitochondria

Play Episode Listen Later Jan 1, 1978

Sun, 1 Jan 1978 12:00:00 +0100 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7CV2-4B42H29-B4&_user=616146&_coverDate=12%2F31%2F1979&_rdoc=21&_fmt=high&_orig=browse&_srch=doc-info(%23toc%2318066%231979%23999449999%23472657%23FLA%23display%23Volume)&_cdi=18066&_sort=d&_docanc https://epub.ub.uni-muenchen.de/7323/1/7323.pdf Weiss, Hanns; Neupert, Walter; Sebald, Walter ddc:610, Medizin

sun preparation weiss medizin mitochondria sebald hanns neurospora articleurl 23volume coverdate

Transport of Cytoplasmically Synthesized Proteins into the Mitochondria in a Cell Free System from Neurospora crassa

system transport import medizin proteins synthesis mitochondria synthesized cell free neurospora

Play Episode Listen Later Dec 1, 1977

Synthesis and transport of mitochondrial proteins were followed in a cell-free homogenate of Neurospora crassa in which mitochondrial translation was inhibited. Proteins synthesized on cytoplasmic ribosomes are transferred into the mitochondrial fraction. The relative amounts of proteins which are transferred in vitro are comparable to those transferred in whole cells. Cycloheximide and puromycin inhibit the synthesis of mitochondrial proteins but not their transfer into mitochondria. The transfer of immunoprecipitable mitochondrial proteins was demonstrated for matrix proteins, carboxyatractyloside-binding protein and cytochrome c. Import of proteins into mitochondria exhibits a degree of specificity. The transport mechanism differentiates between newly synthesized proteins and preexistent mitochondrial proteins, at least in the case of matrix proteins. In the cell-free homogenate membrane-bound ribosomes are more active in the synthesis of mitochondrial proteins than are free ribosomes. The finished translation products appear to be released from the membrane-bound ribosomes into the cytosol rather than into the membrane vesicles. The results suggest that the transport of cytoplasmically synthesized mitochondrial proteins is essentially independent of cytoplasmic translation; that cytoplasmically synthesized mitochondrial proteins exist in an extramitochondrial pool prior to import; that the site of this pool is the cytosol for at least some of the mitochondrial proteins; and that the precursors in the extramitochondrial pool differ in structure or conformation from the functional proteins in the mitochondria.

Kinetic Studies on the Transport of Cytoplasmically Synthesized Proteins into the Mitochondria in Intact Cells of Neurospora crassa

studies individual transport medizin cells proteins mitochondria kinetic intact mitochondrial synthesized neurospora

Play Episode Listen Later Dec 1, 1977

The transport of cytoplasmically synthesized mitochondrial proteins was investigated in whole cells of Neurospora crassa, using dual labelling and immunological techniques. In pulse and pulse-chase labelling experiments the mitochondrial proteins accumulate label. The appearance of label in mitochondrial protein shows a lag relative to total cellular protein, ribosomal, microsomal and cytosolic proteins. The delayed appearance of label was also found in immunoprecipitated mitochondrial matrix proteins, mitochondrial ribosomal proteins, mitochondrial carboxyatractyloside-binding protein and cytochrome c. Individual mitochondrial proteins exhibit different labelling kinetics. Cycloheximide inhibition of translation does not prevent import of proteins into the mitochondria. Mitochondrial matrix proteins labelled in pulse and pulse-chase experiments can first be detected in the cytosol fraction and subsequently in the mitochondria. The cytosol matrix proteins and those in the mitochondria show a precursor-product type relationship. The results suggest that newly synthesized mitochondrial proteins exist in an extra-mitochondrial pool from which they are imported into the mitochondria.

The 73 S ribosome of Neurospora crassa is the native mitochondrial ribosome

inclusion native medizin mitochondria mitochondrial rnas edta mg2 ribosome neurospora

Play Episode Listen Later Jan 1, 1977

The effect of the inclusion of EDTA and of heparin, in media used in the isolation of mitochondria, on the mitochindrial previous termribosomenext term has been investigated. 1. 1. Mitochondria isolated from previous termNeurospora crassanext term in the presence of EDTA contain only a single type of monomeric previous termribosome, viz. 73next term S. 2. 2. Mitochondria isolated in the presence of Mg2+ contain both 79-S and previous term73next term-S monomeric previous termribosomes.next term The heterogeneity of the previous termribosomesnext term was demonstrated by (a) ultracentrifugation on sucrose gradients, (b) electron microscopy, (c) immunoprecipitation with antibodies against mitochondrial previous term73next term-S and 79-S cytoplasmic previous termribosomes,next term (d) gel electrophoresis of high and low molecular weight RNAs. 3. 3. Inclusion of heparin in all media used for the isolation of mitochondria and previous termribosomesnext term resulted in (a) dissociation of previous term73next term-S mitochondrial previous termribosomesnext term into 50-S and 37-S subunits; (b) stabilization of 79-S cytoplasmic previous termribosomes;next term (c) in the case of mitochondria isolated in the presence of Mg2+ containing both previous term73next term-S and 79-S previous termribosomes,next term heparin causes the selective dissociation of the previous term73next term S monosome to yield previous termribosomesnext term containing only a single monomeric previous termribosomenext term type, viz. 79 S. 4. 4. It is concluded that (a) the 79-S previous termribosomesnext term present in mitochondria isolated in the presence of Mg2+ are contaminating cytoplasmic previous termribosomes,next term (b) the previous term73next term-S previous termribosomesnext term are the real functional mitochondrial previous termribosomes of Neurospora crassanext term.

Translation products in isolated mitochondria from Neurospora crassa

products translation werner medizin isolated mitochondria sigurd neurospora

Play Episode Listen Later Jan 1, 1976

Thu, 1 Jan 1976 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7296/1/7296.pdf Werner, Sigurd; Neupert, Walter; Rücker, Axel von ddc:610, Medizin

Significance of 80-S ribosomes associated with Neurospora crassa mitochondria

significance fritz medizin rainer gerhard mitochondria neurospora

Play Episode Listen Later Jan 1, 1976

Thu, 1 Jan 1976 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7304/1/7304.pdf Neupert, Walter; Miller, Fritz; Harmey, Matthew A.; Hallermayer, Gerhard; Michel, Rainer ddc:610

Partial sequence of a chloroform-methanol soluble polypeptide from Neurospora mitochondrial membranes

Play Episode Listen Later Jan 1, 1976

Thu, 1 Jan 1976 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7306/1/7306.pdf Wachter, Elmar; Neupert, Walter; Michel, Rainer; Machleidt, W.

medizin partial sequence rainer elmar mitochondrial wachter soluble membranes methanol chloroform polypeptide neurospora

Coordination of mitochondrial and cytoplasmic protein synthesis in Neurospora crassa

medizin coordination mitochondrial protein synthesis cytoplasmic neurospora

Play Episode Listen Later Jan 1, 1976

Thu, 1 Jan 1976 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7307/1/7307.pdf Rücker, Axel von; Neupert, Walter

Action of intracellular proteinases on mitochondrial translation products of Neurospora crassa and Schizosaccharomyces pombe

action products translation medizin rainer hartmann mitochondrial intracellular neurospora

Play Episode Listen Later Jan 1, 1975

Wed, 1 Jan 1975 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7293/1/7293.pdf Neupert, Walter; Hartmann, A.; Liebl, A.; Michel, Rainer

Isolation and characterization of a mitochondrially synthesized polypeptide from Neurospora crassa cni-1 mutant

Play Episode Listen Later Jan 1, 1975

Wed, 1 Jan 1975 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7284/1/7284.pdf Neupert, Walter; Otto, J.; Machleidt, W.; Liebl, A.; Michel, Rainer

isolation medizin mutant rainer characterization synthesized polypeptide neurospora

Synthesis of cytochrome oxidase components in isolated mitochondria of Neurospora crassa

Play Episode Listen Later Oct 15, 1974

Tue, 15 Oct 1974 12:00:00 +0100 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T36-447P02V-2S&_user=616146&_coverDate=10%2F15%2F1974&_rdoc=22&_fmt=high&_orig=browse&_srch=doc-info(%23toc%234938%231974%23999529997%23268635%23FLP%23display%23Volume)&_cdi=4938&_sort=d&_docancho https://epub.ub.uni-muenchen.de/7275/1/Neupert_Walter_7275.pdf Neupert, Walter; Werner, Sigurd; Rücker, Axel von

werner medizin components isolated synthesis mitochondria sigurd cytochrome oxidase neurospora articleurl neupert walter coverdate 23volume 23flp

Immunological difference of mitochondrial and cytoplasmic ribosomes of Neurospora crassa

Play Episode Listen Later May 1, 1974

Wed, 1 May 1974 12:00:00 +0100 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T36-44W4WF3-3F&_user=616146&_coverDate=05%2F01%2F1974&_rdoc=21&_fmt=high&_orig=browse&_srch=doc-info(%23toc%234938%231974%23999589997%23280309%23FLP%23display%23Volume)&_cdi=4938&_sort=d&_docancho https://epub.ub.uni-muenchen.de/7268/1/Neupert_Walter_7268.pdf Neupert, Walter; Hallermayer, Gerhard

medizin gerhard mitochondrial immunological cytoplasmic neurospora articleurl neupert walter coverdate 23volume 23flp

Edeine Inhibition and Resistance in Neurospora

Play Episode Listen Later Jan 1, 1974

Tue, 1 Jan 1974 12:00:00 +0100 http://www.springerlink.com/content/h6t76u288422wm74/?p=1c84c9fab9fa4ff6abfeeb3ba5a8fd2f&pi=9 https://epub.ub.uni-muenchen.de/7282/1/Neupert_Walter_7282.pdf Neupert, Walter; Klingmüller, Walter; Wagenmann, Margit ddc:610, Medizin

resistance medizin inhibition neurospora neupert walter

Precursors of Cytochrome Oxidase in Cytochrome-Oxidase-Deficient Cells of Neurospora crassa

Play Episode Listen Later Jan 1, 1974

Three different cell types of Neurospora crassa deficient in cytochrome oxidase were studied: the nuclear mutant cni-1, the cytoplasmic mutant mi-1 and copper-depleted wild-type cells. * 1. The enzyme-deficient cells have retained a functioning mitochondrial protein synthesis. It accounted for 12–16% of the total protein synthesis of the cell. However, the analysis of mitochondrial translation products by gel electrophoresis revealed that different amounts of individual membrane proteins were synthesized. Especially mutant cni-1 produced large amounts of a small molecular weight translation product, which is barely detectable in wild-type. * 2. Mitochondrial preparations of cytochrome-oxidase-deficient cells were examined for precursors of cytochrome oxidase. The presence of polypeptide components of cytochrome oxidase in the mitochondria was established with specific antibodies. On the other hand, no significant amounts of heme a could be extracted. * 3. Radioactively labelled components of cytochrome oxidase were isolated by immunoprecipitation and analysed by gel electrophoresis. All three cell types contained the enzyme components 4–7, which are translated on cytoplasmic ribosomes. The mitochondrially synthesized components 1–3 were present in mi-1 mutant and in copper-depleted wild-type cells. In contrast, components 2 and 3 were not detectable in the nuclear mutant cni-1. Both relative and absolute amounts of these polypeptides in the enzyme-deficient cells were quite different from those in wild-type cells. * 4. The components of cytochrome oxidase found in the enzyme-deficient cells were tightly associated with the mitochondrial membranes. * 5. Processes, which affect and may control the production of enzyme precursors or their assembly to a functional cytochrome oxidase are discussed.

processes medizin cells mitochondrial deficient precursors cytochrome oxidase neurospora

Lipid composition of mitochondrial outer and inner membranes of Neurospora crassa

medizin composition outer gerhard lipids mitochondrial membranes neurospora

Play Episode Listen Later Jan 1, 1974

Tue, 1 Jan 1974 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7267/1/7267.pdf Neupert, Walter; Hallermayer, Gerhard ddc

Degradation of mitochondrial translation products in Neurospora crassa

Play Episode Listen Later Jan 1, 1974

Tue, 1 Jan 1974 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7266/1/7266.pdf Neupert, Walter; Rücker, Axel von ddc:610, Mediz

products translation medizin degradation mitochondrial mediz neurospora

Mitochondrial Translation Products before and after Integration into the Mitochondrial Membrane in Neurospora crassa

products integration translation medizin gel rna membrane mitochondrial nascent neurospora

Play Episode Listen Later Jan 1, 1973

# 1. Nascent translation products on mitochondrial ribosomes were selectively labeled in vivo in the presence of cycloheximide with radioactive leucine. They were isolated together with the ribosomes. # 2. The labeled polypeptides show a high tendency to aggregate and can only be kept in solution in the presence of detergents such as dodecylsulfate. Also, mitochondrial ribosomes carrying nascent peptide chains easily form aggregates. # 3. The polypeptides adhering to mitochondrial monomeric ribosomes differ from those adhering to polymeric ribosomes. Gel electrophoresis in the presence if dodecylsulfate shows for the peptidyl transfer RNA products at the monomer, an apparent molecular weight of 27000. After removing the transfer RNA, an apparent molecular weight of less than 10000 is registered. The peptides adhering to mitochondrial polymeric ribosomes display a broad range of apparent molecular weights. In contrast, translation products associated with cytoplasmic monomeric and polymeric ribosomes all show quite disperse molecular weights. # 4. Using gel-chromatographic analysis no difference in the elution characteristics between translation products associated with mitochondrial monomeric and polymeric ribosomes was found. In both cases apparent molecular weights of about 11000 were obtained. # 5. A kinetic study of the appearance of mitochondrial translation products in the mitochondrial membrane was carried out. A conversion process of products with lower apparent molecular weights to those with higher apparent molecular weights is observed. This suggests that mitochondrial ribosomes form polypeptides which are modified during or after integration into the membrane. # 6. The hypothesis is discussed that mitochondria possess their own system of transcription and translation, because the hydrophobic nature of the translation products makes it necessary that they are formed inside the inner mitochondrial membrane, into which they are integrated.

Über die gegenseitige Abhängigkeit von mitochondrialer und cytoplasmatischer Translation bei der Bildung der Innenmembran von Mitochondrien in Neurospora crassa

Play Episode Listen Later Jan 1, 1973

Mon, 1 Jan 1973 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7264/1/7264.pdf Neupert, Walter; Michel, Rainer; Rücker, Axel von

translation bildung medizin rainer mitochondrien neurospora innenmembran

Structure and biogenesis of outer and inner mitochondrial membrane of Neurospora crassa

Play Episode Listen Later Jan 1, 1972

Sat, 1 Jan 1972 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7184/1/7184.pdf Pfaller, A.; Ludwig, George D.; Neupert, Walter

structure ludwig medizin outer membrane mitochondrial biogenesis george d pfaller neurospora

Sites of Biosynthesis of Outer and Inner Membrane Proteins of Neurospora crassa Mitochondria

Play Episode Listen Later Apr 1, 1971

Outer and inner membranes of Neurospora crassa mitochondria were separated by the combined swelling, shrinking, sonication procedure. Membranes were characterized by electron microscopy and by marker enzyme activities. A red carotenoid pigment was found to be concentrated in the outer membrane. The inner mitochondrial membrane was resolved into about 20 protein bands on polyacrylamide gel electrophoresis, whereas the outer membrane shows essentially one single protein band. Only negligible incorporation of radioactive amino acids occurs into outer membrane when isolated mitochondria are synthesizing polypeptide chains. In agreement with this observation labeling of outer membrane protein is almost entirely blocked, when whole Neurospora cells are incubated with radioactive amino acids in the presence of cycloheximide, an inhibitor of cytoplasmic protein synthesis. Finally, the essential electrophoretic protein band from outer membrane does not become labeled when mitochondria are incubated with radioactive amino acids either in vitro or in vivo in the presence of cycloheximide. It is concluded that the vast majority, if not all, of the outer membrane protein is synthesized by the cytoplasmic system and that polypeptide chains formed by the mitochondrial ribosomes are integrated into the inner mitochondrial membrane.

sites medizin outer mitochondria membranes biosynthesis membrane proteins neurospora

Amino acid incorporation into mitochondrial ribosomes of Neurospora crassa wild-type and Mi-1 mutant

Play Episode Listen Later Jan 1, 1971

Fri, 1 Jan 1971 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7179/1/7179.pdf Pfaller, A.; Massinger, P.; Neupert, Walter

medizin mutant amino acids incorporation mitochondrial wild type pfaller neurospora

Zur Biosynthese de Proteine der mitochondrialen Aussen- und Innenmembranen in Neurospora crassa

Play Episode Listen Later Jan 1, 1970

Thu, 1 Jan 1970 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7174/1/7174.pdf Neupert, Walter

medizin proteine aussen neurospora biosynthese

Incorporation in vivo of 14C-Labelled Amino Acids into the Proteins of Mitochondrial Ribosomes from Neurospora crassa Sensitive to Cycloheximide and Insensitive to Chloramphenicol

vivo medizin radioactive proteins amino acids incorporation insensitive mitochondrial labelled neurospora

Play Episode Listen Later Oct 1, 1969

Radioactive amino acids were incorporated in vivo into Neurospora crassa cells, and the mitochondrial ribosomes were isolated. The incorporation of radioactivity into the proteins of these ribosomes was inhibited by cycloheximide, but not by chloramphenicol. It is therefore concluded that these proteins are synthesized on the cycloheximide sensitive and chloramphenicol insensitive cytoplasmic ribosomes.

Puromycin Sensitivity of Ribosomal Label after Incorporation of 14C-Labelled Amino Acids into Isolated Mitochondria from Neurospora crassa